I was just thinking about something. . . Harry got his invisibility cloak in SS/PS, so in CoS, why didn't the trio just throw the cloak over themselves, and follow Draco, or any other Slytherin to their common room and sit and listen to see what was said? I know the side story of making the potion was good, and the need to have privacy to make the potion is what brought them to Myrtle's bathroom, and the entrance to the chamber itself. But, just wondering why they never thought of it, it would have also allowed them more time to listen than the effects of the potion did. any thoughts?